An Investigation into the Ability of Adults with Post-Stroke Aphasia to Learn New Vocabulary

Abstract

Recent studies have established that adults with post-stroke aphasia can learn to establish connections between familiar words and abstract images, and nonwords with familiar objects. What has not been investigated was whether adults with aphasia could learn non-words with abstract images/ novel meanings i.e. new vocabulary. The main objective of this study was to investigate whether adults with post-stroke aphasia could learn 'novel' word forms with 'novel' word meanings, despite phonological and/or semantic impairment. Specific research questions included: Can post-stroke adults with aphasia learn new vocabulary? If so, what factors affect their capacity to learn? Is it possible to predict which individuals will learn most successfully? The methodology was developed using preliminary studies both with adults of normal language and cognitive functioning and post-stroke non-aphasic and aphasic adults. It incorporated learning theory and a cognitive neuropsychological model of language. A range of assessments was used to facilitate the capture of new learning. 'New learning' was measured not only in terms of the accurate production of the new stimuli but also the recognition and knowledge of the word forms and meanings of this new vocabulary. In the main investigation twenty novel word forms with 20 novel meanings were taught to 12 aphasic adults (< 65 years), over a four day period, using an errorless learning paradigm. Immediate recall of these newly learnt representations was investigated as well as delayed recall. Quantitative and qualitative results from a case series of 12 participants are presented and discussed. Despite semantic and phonological difficulties, all but three participants demonstrated substantial learning of the new vocabulary. The participants' range of learning ability (from both immediate and delayed recall data) was analysed in relation to severity of aphasia, cognitive factors (including attention, memory and executive function), as well as variables such as age, months post-stroke and number of years in education. With an intensive training period, these participants with aphasia demonstrate varying degrees of ability for new learning. Possible influencing factors and implications for speech and language therapy rehabilitation are discussed.